Light diffusing system



June 4, 1957 M. H; muse-R LIGHT DIFFUSING SYSTEM 3 Sheets-Sheet 1 Filed March 5, 1954 w R I. I Is e l- WW. I, RQw

BY 0V 4/: ATTORNEY.

June 4, 1957 M. H. KRUGER 2,794,903

LIGHT. DIFFUSING SYSTEM Filed March 5. 1954 A 3 Sheets-Sheet 2 3 5. ll H i Si i Q i 11 l vb I Q'w l I L i INIEiTOR.

June 4, 1957 M. H. KRUGER 2,794,903

LIGHT DIFFUSING SYSTEM Filed March 5. 1954 s Sheets-Sheet s [is arr-kiwi) Unite States Patent LIGHT DEFUSING SYSTEM Michael Henry Kruger, Chestnut Hill, Mass, assignor to A. L. Smith Iron Company, Chelsea, Mass, :1 corporation of Massachusetts Application March 5, 1954, Serial No. 414,246

5 Claims. (Cl. 240-9) This invention relates to light diffusing systems in general and more especially to plastic light diffusing partitions in association with tubular fluorescent lamps.

In area illumination, various diffusing devices have been employed, not only to produce a predetermined decorative lighting effect, but in an attempt to reduce the cost of construction, installation and upkeep. Eggcrate louver s, light transmitting translucent glass and plastic partitions have been extensively employed; due however in part to their rigidity and weight, required rather formidable and durable fastening means. In view of the foregoing, among the objects of the present invention it is aimed to provide in association with tubular fluorescent lamps an improved light diffusing partition, light in weight, and which can be manufactured at low cost, and installed with facility without any extraneous fastening devices at a minimum cost.

More specifically, it is aimed to provide a yieldable plastic light transmitting, translucent partition or diffuser having preformed end portions which can be easily snapped between opposing abutments, such as opposing tubular fluorescent lamps and between tubular fluorescent lamps and unilluminated abutments such as wall moldings and opposing unilluminated abutments without extraneous fastening means, relying upon the elasticity in the partition per se and the immunity of the partition to the heat generated by the lamp to maintain the preformed end portions in gripping engagement with the lamps and abutments.

It is still another object of the present invention to provide a sheet composed of a plastic material which is insensible or immune to the heat generated by the average tubular fluorescent lamp of between 140 F. and 160 F. when transmitting light and which sheet is provided with preformed end portions at opposite ends which can engage two of such adjacent parallel tubular lamps while transmitting light, relying upon the elasticity or tendency from a slightly flexed abnormal condition to a straightened out normal condition, to maintain the preformed end portions in engagement with the engaged lamps.

It is still another object of the present invention to provide a sheet or diffuser composed of a light transmitting, translucent, readily flexible, plastic material such as a biaxially oriented polystyrene having preformed ends to engage tubular fluorescent lamps and the like, so that the light transmitted by the lamps may be directed either through one or two thicknesses of the plastic sheet to produce a combination of light rays either by having one bundle of light rays pass through a single thickness of the sheet to a ceiling or the like deflector to be deflected and transmitted through a second sheet in combination with a second bundle of light rays passing through one thickness of the sheet and directed then to be transmitted through the second thickness of sheet, or in turn a combination of light rays passing through one thickness of a plastic sheet in combination with a second bundle of light rays passing through one thickness of the sheet and deflected from the outer face of a second thickness of the sheet together with a third bundle of light rays passing through two "ice thicknesses of the plastic sheet to a deflector such as a ceiling, and in turn deflected by the ceiling back through one of the thicknesses of plastic material.

It is still another object of the present invention to provide a light transmitting medium creating two light intensities, one greater than the other, on the opposite faces of a light diffusing panel or diffuser.

These and other features, capabilities and advantages of the present invention will appear from the subjoined detailed description of specific embodiments thereof illustrated in the accompanying drawings in which Fig. 1 is a perspective of a single lighting fixture closed at its ends equipped with a plurality of light diffuser sheets made according to the present invention.

Fig. 2 is a plan view looking downwardly, partly broken away of a-plurality of lighting fixtures similar to those illustrated in Fig. 1, arranged end to end.

Fig. 3 is a transverse section of the embodiment shown in Fig. 1.

Fig. 4 is an enlarged fragmental transverse section showing an additional embodiment.

Fig. 5 is an enlarged transverse section on the line 55 of Fig. 2.

Fig. 6 is an enlarged fragmental longitudinal section on the line 66 of Fig. 1.

Fig. 7 is an enlarged fragmental section on the line 77 of Fig. 2.

Fig. 8 illustrates diagrammatically in a dotted line the position of a partition before engaging two lamps and in full line the position of this partition when engaging the two lamps.

Fig. 9 illustrates diagrammatically the direction of the light rays transmitted from a lamp.

Figs. 10 and 11 are end and side views in cross section, respectively, more or less diagrammatically of an illuminated ceiling.

Fig. 12 is an end view in section more or less diagrammatically of an illuminated side wall, and Fig. 13 is a front elevation more or less diagrammatically of the illuminated side wall illustrated in Fig. 12.

Fig. 14 shows another embodiment diagrammatically illustrating the partitions snapped reversed to-the position shown in Fig. 9.

From the embodiments shown, it will appear that the invention resides primarily in the use of a light transmitting, translucent material or diffuser which is flexible so that when formed in a sheet with preformed gripping ends, and the sheet flexed, the inherent tendency from this abnormal flexed condition to its norm-a1 straightened out condition will not only cause the ends of the sheet effectively to grip opposing abutments, including lamps, between which the sheet extends, but the sheet be immune to softening from the heat generated by the lamps to maintain the elastic characteristic necessary effectively to grip the abutments and to enable flexing the sheet to remove it after having been subjected to the heat of the gripped lamp. When using cold light transmitting lamps, such as cathode tubes, as the sheet supporting abutments heed need only be given that the plastic material selected is flexible in addition to being translucent so that it not only transmits light, but also diffuses the light while trans mitting the same. On the other hand, when heat generating lamps are used such as the conventional fluorescent tubular lamps which generate heat of a temperature of about F. to F. when transmitting light, it is only necessary that the plastic material selected is immune or resistant to temperatures of from 140 F. to 160 F. -It has been found that when the plastic material selected is a biaxially oriented plastic substance or a substance composed of polystyrene, excellent results have been achieved.

In the embodiment illustrated in Fig. 1 there is shown a lighting fixture having a main housing 1 which is connected to the ceiling by any suitable means, not shown, either direct to the ceiling or by hangers engaging the, shoulders 2 to which hou-singlthe end frames 3 and 4 are secured by means of-the angle'clips S-and 6; The end frames 3 and 4 preferablycomplement one another, the end frame 3 being provided with anelongated socket 7; such as disclosed in Fig. 6, equipped with the conventional yieldable seat, and-the end frame 4 provided with a narrow socket, such'as the narrow socket 8 of the embodiment shown in Fig. 7, equippedwith the conventional fixed seat to receive the ends of a flourescent tubular lamp, such as the lamp 9--'disclosed in Fig. 6. When a single set of parallel tubes 9 is required, then the end frames 3and 4 are preferably closed by the closure end frames 10and1'1; respectively. In'the embodiment illustrated in Figs. 1and'3, the ends of the end frames 3 and-4 are connected by the sheet metal brackets constituting abutments Hand 13 having the-inwardly and upwardly flaring flanges 14 and 15, respectively. The end frame 3, in turn, is providedwith three elongated lamp sockets 7 in alinement with three elongated fixed lamp sockets in the end frame 4 to receive the three fluorescent tubular lamps 16, Hand 18, such as the lamp 9 of Fig. 6, which in the present instance are equally spaced from one another, with the two outermost lamps 16 and 18- disposed-a shorter distance from the side brackets 12 and 13 than from the intermediate lamp 17.

Between the lamps 16*and 17; and the lamps 17 and 18, constituting abutments there are suspended the light diffusing sheets or diffusers 19' and'20, respectively, of substantially equal width to one another and otherwise equally conformed to one another, each having a substantially wide upwardly curved intervening sheet formation 21 terminating along its longitudinally extending sides in the serpentine forms 22, each consisting of a large curved portion or jaw forming gripping end 23 intermediate the two reversely curved small curved portions 24 and 25, the small curved portion 24 being disposed intermediate the sheet formation 21 and the large curved portion 23 and the small curved portion 25 being disposed adjacent the outer edge of the serpentine form 22,

The diffusers or sheets 19 and 20 are preferably composed of a flexible light transmitting, translucent material such as a biaxially oriented substance, or a composition of polystyrene, of about .015 inch in thickness immune to softening from the heat generated by the lamps 16 and 17 of between 140 F. and 160 F. With sheets of these characteristics and thicknesses, the same may be snapped between the two lamps 16 and 17, as an instance, by merely flexing the sheet formation 21 as shown in Fig. 8, until the enlarged curved portions 23 engage the outer cylindrical surfaces of the lamps 16 and 17, and

then releasing the same when the natural tendency of the sheet formation 21 to resume its normally straightened out position will cause the enlarged curved portions 23 effectively to grip the lamps 16 and 17.

In some instances, as is the case with the short diffusers,

or sheets 26 and 27, the ends engaging the molding strips or flanges 14 and are more or less S-shaped, each having a hook portion 28 to receive the flange 14, 15, and a curved portion 29 intermediate the sheet formation 30 and the hook portion 28. The other preformed end of each of the sheets 26 and 27 is formed similar to the ends of the sheets 19 and so that they will grip the,

lamps 16 and 17.

If, instead of thetsingle flange bracket 12 of Fig. 3, two single flange brackets are secured to hanger rod 31, such as the bracket combination 32 shown in Fig. 4, having the upwardly flaring flanges 33 and 34,. then obviously the ends 35 of the sheets 36 will be conformed similar to the end formation 37 of the ,sheet26 of Fig. 3

and the ends 38 conformed similar to the end formation 22 of the sheet 19, in which case the bracket conformation 32 may be used not only to connect the sides of two lighting fixtures to one another, such as the lighting fixture illustrated in Fig. 1, but also to receive rods, such as rod 31 to connect the lighting fixture to the ceiling.

In some cases, as is the case with the embodiment illustrated in Fig. 2, the housing 39 in place of the housing 1 of the embodiment illustrated in Fig. 1, may be connected to the hanger rods 40 extending down from the ceiling, which hanger rods 40 are connected by the jaws 41 and 42 to the housing 39, which jaws 41 and 42 engage recesses, such as the recesses 43 and 44, respectively, of the housing 1 illustrated in Fig. 1. In some instances, however, with or without the hangers 40, the lighting fixture may be connected to the ceiling by hanger rods 45 connected by the jaws 46 to the bracket combinations 47 similar to the bracket combination 32 illustrated in Fig. 4. If a bracket combination 47 as shown in Fig. 5 is interposed between two adjacent parallel lamps 52 and 53, then-the combination bracket 47 could be bypassed by the plastic sheet or diffuser 49, and the plastic sheet 49 connected by its preformed ends 50 and 51 to the lamps 52 and 53, respectively, similar to the connection of the sheet 19 to the lamps 16 and 17 of the embodiment illustrated in Fig. 3.

In turn, if several lengths of lighting fixtures are disposed end to end, see Fig. 7, end frames, such as the end frames 54 and 55 of the embodiment illustrated in Fig. 2, are disposed adjacent to one another. In other words, each end frame 55 at the left hand'end as an instance of a'lighting fixture unit will be similar to the end frame 55 at the left hand end of the adjacent lighting fixture unit, and the end frame 54 of the adjacent lighting fixture unit in engagement with the end frame 55 of the first-mentioned lighting fixture unit will be disposed at the right hand end as an instance of the adjacent lighting fixture unit. Here to facilitate nesting the end frames 54 and 55 into as compact a lateral package as possible, the end frame 54 will be provided with the fixed narrow lamp socket 8 of the 'lamp 56, and the end frame 55 provided with the extended lamp socket 57 of the lamp 58 having the yieldable seat, similar to the extended lamp socket 7 of the embodiment illustrated in Fig. 6, will project over from the end frame 55 of one lighting fixture unit into the end frame 54 of the adjacent lighting fixture unit.

With plastic sheets or diffusers, such as the sheets 59 of the embodiment illustrated in Fig. 9, the light transmittance may theoretically be divided into two groups of intensities, one group'of a predetermined intensity as an instance passing upwardly of the imaginary plane 60 extending diametrically through the lamps 61 and 62, shown as horizontal in Fig. 9, and the other group of a lesser intensity extending downwardly from this plane. Assumingthat the plastic sheets 59 have a transmission efliciency of and a reflectance etficiency of 10%, and there is a loss by absorption of about 10%, the intensity of the light on the two sides of the theoretical plane 60 will be substantially as follows: 50% of the light rays directed upwardly of said theoretical plane 60 multiplied by 80% of the light transmitted, equals 40% plus.

50% of the light rays directed downwardly of said theoretical plane 60 multiplied by 80% of the light transmitted, and in turn multiplied-by 10% of the light reflectedupwardly from the upper face of a sheet 59, equals 4% when the total light so transmitted will equal 44% through the enlarged curved portion or jaw forming gripping ends 63, a single diflusion.

Onthe other hand, the total light transmitted by the light rays directed downwardly of said theoretical plane 60 will be substantially as follows: 50% of the light rays directed downwardly of said theoretical plane 60 multiplied by 80% for the first transmittance through the en- 'largedportion or jaw forming gripping ends 63, in turn multiplied-by a second 80% for the second transmittance through the intervening sheet portion 64 will equal a total light transmittance with a double diffusion of 32%.

As a result of this construction, it will thus appear that on one side of the sheet portion 64 there will be transmitted one light intensity of diffused light, characterized by a single diffusion transmitting 44% of the total light transmitted, and on the othher side of the sheet portion 64 there will be transmitted a lesser light intensity of diffused light, characterized by a double diffusion approximating 32% of the total light transmitted, whereby two adjacent room areas in the interest of predetermined lighting effects may with facility have two diffused light areas of different light intensities. If the sheet portions 64 approximated a vertical plane instead of a horizontal plane as shown in Fig. 9, instead of room areas of different levels, room areas adjacent to one another on the same level could of course be provided with light intensities differing from one another without departing from the general spirit of the invention.

This direction of the light rays would of course be substantially reversed if the panels or sheets 59 were snapped on upside down as shown in Fig. 14.

In Figs. and 11 there is illustrated diagrammatically an illuminated ceiling construction 65 made according to the present invention, Fig. 10 showing an end view of the ceiling structure in cross section, and Fig. 11 a side view in cross section. In Figs. 12 and 13, in .turn, there is illustrated diagrammatically an illuminated side wall structure 66 made according to the present invention, Fig. 12 showing an end view of the illuminated side wall in cross section, and Fig. 13 showing a front elevation of the same.

It is obvious that various changes and modifications may be made to the details of construction without departing from the general spirit of the invention as set forth in the appended claims.

I claim:

1. The diffuser for a lighting system disposed between two areas, the lighting system having a plurality of opposing abutments, said opposing abutments being adjacent parallel fluorescent tubular lamps, said diffuser consisting of sheets of flexible, light transmitting, translucent material having preformed jaw forming gripping ends at opposite sides gripping two adjacent lamps, the adjacent jaw forming ends gripping a single lamp, and entirely covering the same, the flexibility of the sheets enabling the same to be flexed when positioning the sheets into and out of gripping engagement of the jaw forming gripping ends with said lamps, and enabling the tendency of the sheets to resume their normal shape to effect intimate gripping engagement of the jaw forming gripping ends with said lamps, thereby in turn enabling the light of different intensities to emanate from opposite sides of said diffuser.

2. The diffuser for a lighting system disposed between two areas, the lighting system having opposing abutments, at least one of said abutments being a tubular lamp, said diffuser consisting of sheets of flexible, light transmitting, translucent material having preformed jaw forming ends at opposite sides, gripping and covering said opposing abutments, the flexibility of the sheets enabling the same to be flexed when positioning the sheets into and out of gripping engagement of the jaw forming ends with said abutments and enabling the tendency of the sheets to resume their normal shape to effect intimate gripping engagement of the jaw forming ends with said abutments, thereby enabling the light of different intensities to emanate from opposite sides of said diffuser.

3. The diffuser for a lighting system disposed between two areas, the lighting system having a plurality of opposing abutments, said opposing abutments being adjacent parallel fluorescent tubular lamps, said diffuser consisting of sheets of flexible, light transmitting, translucent material having preformed jaw forming ends at opposite sides gripping and covering two adjacent lamps, the flexibility of the sheets enabling the same to be flexed when positioning the sheets into and out of gripping engagement of the jaw forming ends with said lamps, and enabling the tendency of the sheets to resume their normal shape to effect intimate gripping engagement of the jaw forming ends with said lamps, thereby enabling the light of different intensities to emanate from opposite sides of said diffuser.

4. The diffuser for a lighting system having a tubular lamp and an adjacent parallel abutment, said diffuser consisting of a sheet of flexible, light transmitting, translucent material having preformed jaw forming ends, along opposite sides gripping and covering said lamp and abutment, the flexibility of the sheet enabling the sheet to be flexed when positioning the same into and out of gripping engagement of the jaw forming ends with said lamp and abutment and enabling the tendency of the sheet to resume its normal shape to effect intimate gripping engagement of the jaw forming ends with said lamp and abutment, thereby enabling the light of different intensities to emanate fromopposite sides of said diffuser.

5.. The diffuser for a lighting system having a plurality of opposing abutments, at least one of said abutments being a tubular fluorescent lamp, said diffuser consisting of sheets of flexible, light transmitting, translucent material immune to the heat generated by the lamp and having preformed jaw forming ends along opposite sides gripping and covering said abutments, the flexibility of the sheets enabling the same to be flexed when positioning the sheets into and out of gripping engagement of the jaw forming ends with said abutments, and enabling the tendency of the sheets to resume their normal'shape to effect gripping engagement of the jaw forming ends with said abutments, thereby enabling the light of different intensities to emanate from opposite sides of said diffuser.

References Cited in the file of this patent UNITED STATES PATENTS 2,054,846 Zillger Sept. 22, 1936 2,258,354 Doane Oct. 7, 1941 2,312,866 Boudier Mar. 2, 1943 2,366,216 Roberts Jan. 2, 1945 2,381,792 Wakefield Aug. 7, 1945 2,516,660 Versen July 25, 1950 2,583,939 French June 29, 1952 2,643,328 Elmendorf June 23, 1953 

